1. Technical Field
The present invention relates generally to an apparatus, method and computer program for controlling a storage device, and more particularly to a control apparatus, the storage device, a control method, and a computer program for controlling data transmission and reception performed by the storage device with an external apparatus.
2. Related Art
In recent years, a system for implementing disaster countermeasures has been put in practical use by connecting server devices or disk units via wide area networks using fiber channels to perform remote backup of data. In this system, high reliability is required for a communication line employed for the wide area network. For this reason, in many cases, both of a communication line for general use and a communication line for backup are prepared in advance. As a result of this, even if an error should occur in one communication line, the communication would be able to be continued with the other communication line.
In order to reduce maintenance costs or the like, the communication line for backup has a bandwidth smaller than that of the communication line for general use in many cases. For this reason, the bandwidth of the communication is different between the cases of using the communication line for general use and using the communication line for backup.
Specifically, data to be transmitted from a storage device to the outside are once stored in a buffer provided in a host bus adapter, and are read from the buffer at timings according to the bandwidth of the communication line and transmitted therefrom. A control apparatus for communication control provided in the storage device periodically detects whether or not the buffer space is available, and if the buffer is available, the control apparatus reads data out of a recording unit (for example, archive media such as a magnetic disk) to store the data in the buffer. By preparing such buffers, even where the bandwidth of an external communication line varies to some extent, the data can be transmitted continuously.
As a reference technique, there has conventionally been proposed a technique in which, regarding a storage device connected to the network, an upper limit of the communication bandwidth for the storage device to communicate with another apparatus is calculated based on a limit on the performance of the storage device (for example, data such as an access speed of a disk or the like), and bandwidth guarantee in the network is provided on the basis of the upper limit (see Japanese Unexamined Patent Publication (Kokai) No. 2004-48124).